Field of the Invention
The present invention relates to a method for regulating the control of an electrical actuator of a valve permitting the exhaust gases of an internal combustion engine to be diverted from the fluid supply circuit of a turbine of a turbocharger designed to compress the fresh gases admitted into the air intake circuit of said internal combustion engine.
Description of the Related Art
A valve or obturator for diverting the exhaust gases of a turbocharger turbine is also commonly called a “wastegate” by the person skilled in the art, the two terms being used equally in the remainder of the document. When an electrical actuator of the electric motor type controls such a valve, an H bridge is present in the circuit for controlling the rotation of the electric motor to permit said electric motor to rotate in both rotational directions, in the forward or reverse directions, to open or close the valve.
“Valve” is understood here as any mobile obturator installed in an exhaust pipe or channel and permitting the circulation of a fluid in said pipe or said channel to be regulated, for example of the standard valve type, flap valve type, butterfly valve type, etc.
In order to determine the quantity of exhaust gas which passes through the turbine, it is necessary to ascertain the position of the wastegate indicating the quantity of diverted gas or that passing through the turbine by calibration. Thus, a law for monitoring the flow rate passing through the wastegate is determined for each position thereof for a given engine as a function of the speed of said engine and the atmospheric pressure, resulting in a table of charge air pressures, as a function of the engine speed, the external pressure and the open position of the wastegate. This table of pressures is used by the ECU (Engine Control Unit) of the engine to regulate the turbocharger.
The prior art teaches a method for obtaining/monitoring the position of the wastegate by analog input by means of a position sensor of said wastegate, providing its position in the range of positions thereof between the complete closure and opening of the valve, thus permitting information to be obtained about the quantity of diverted gas and consequently the power/flow rate delivered by the turbocharger. Such a position sensor generally operates on the widely used principle of replicating the position which provides information about the position of the valve by means of a resistive measurement via a variable electrical resistance as a function of the position of the valve. This method of replicating the position is used to provide monitoring of the position of the valve during the regulating phase of the supercharging pressure. The replication of the position is also used to ensure a means of protecting the electric motor for controlling the valve when mechanically stopped, where the permanent current in the motor could then result in the damage thereof.
As indicated above, the engine control unit of the engine needs to ascertain the position of the wastegate to regulate the turbocharger, this regulation comprising a step of transmitting to the electrical actuator of this wastegate an instruction for the position to be reached by said wastegate from a known position.
A supercharging pressure sensor called a PUT (Pressure Upstream Throttle) sensor, is arranged in the known manner in the intake circuit upstream of the butterfly valve for regulating air admitted by negative pressure in the cylinders, and delivers information at this location to the electronic control unit of the engine about the value of the pressure of the air admitted to the engine, corresponding to the supercharging pressure.
A drawback with the system for monitoring the position of the wastegate as disclosed above is that it requires the use of three connection pins on the ECU, whilst the current trend is to minimize the number of such connections. Moreover, the position sensor represents a considerable cost and a potential source of malfunction, in particular, due to wear or to defective electrical contacts.